Method and apparatus for separating magnetic sheets



Aug. 12, 1958 D. E. STEM 2,847,212

METHOD AND-APPARATUS FOR SEPARATING MAGNETIC SHEETS Filed Sepia. 15.1954 INVEN 0 I E. 2 DOA/14155 57 'E BY z METHOD AND APPARATUS FORSEPARATIN G MAGNETIC SHEETS This invention relates to a device forseparating sheets of magnetic material.

Magnets were used in the past for separating sheets of magneticmaterials such as sheets of metal for the purpose of facilitating thepicking up and feeding of individual sheets of metal to machines oroperations. In these previous devices usually a plurality of magnets arearranged on a perpendicular surface or wall to a certain height so thatthe upper magnets are attracted to the sheets from the top of a stackupwardly and thereby separate them. These devices were expensive, heavyto set up, top heavy and subject to breakage.

The primary object of the invention is to provide for the separation ofmagnetic sheets of material, a single magnet which is self-adjustablealong a vertical surface so as to adjust itself to the best position forseparating the top sheets of a stack of magnetic sheets.

Particularly it is an object of the invention to provide a separator formagnetic sheets which travels on a polished perpendicular surface inaccordance with the balance of the horizontal components of magneticattraction to the sheets to be separated and its gravity, as modified bya certain friction on the polished surface, so that the magnet slidesdown on said polished surface until such time that the horizontalcomponent of magnetic attraction to the sheets and the verticalcomponent gravity forces, and downward magnetic pull or component, arebalanced to hold the magnet in position. As sheets are separated andremoved from a stack the magnet automatically lowers itself to separatefurther sheets from the stack, and when these latter are removed themagnet automatically shifts downwardly again to separate the top sheetsof the remaining stack until all the sheets in the stack are soseparated.

I am aware that some changes may be made in the general arrangements andcombinations of the several devices and parts, as well as in the detailsof the construc tion thereof without departing from the scope of thepresent invention as set forth in the following specification, and asdefined in the following claims; hence, I do not limit my invention tothe exact arrangements and combinations of the said device and parts asdescribed in the said specification, nor do I confine myself to theexact details of the construction of the said parts as illustrated inthe accompanying drawings.

With the foregoing and other objects in view, which will be mademanifest in the following detailed description, reference is bad to theaccompanying drawings for the illustrative embodiment of the invention,wherein:

Fig. 1 is a perspective view of a magnetic separating device constructedin accordance with my invention in operation.

Fig. 2 is a cross-sectional view of the device, the section being takenon lines 2-2 of Fig. 1.

Fig. 3 is a somewhat diagrammatic side view of my device in operation ona high stack of sheets.

Fig. 4 is a somewhat diagrammatic side view of my 2,847,212 PatentedAug. 12, 1958 device showing the relative position after a number ofsheets are removed, and

Fig. 5 is a somewhat diagrammatic side view showing the magnet loweredto follow the reduction of the height of the stack of sheets.

In carrying out my invention, I make use of a vertical plate 1 ofnon-magnetic material, which covers the open side of a vertical hollowguide housing 2. A permanent magnet 3 is held in the housing 2 so thatits poles 4 are held in vertically slidable contact with the innersurface 6 of the plate 1. Said inner plate surface 6 is highly polishedto reduce to a minimum frictional resistance to the sliding of themagnet 3 along said surface.

The magnet 3 has a threaded stud 7 extended from its back through avertical slot 8 of the back 9 of the housing 2. The stud 7 and slot 8guide the magnet 3 vertically. A knurled nut 11 on the outside end ofthe stud '7 can be suitably engaged with the back 9 of the housing tohold magnet at top while sheets are stacked, when ready it is loosenedand allowed to drop to automatic separating position.

The housing 2 has a suitable base 12 with suitable braces 13 to supportthe unit in vertical position. The vertical plate 1 is detachably heldon the opening of the housing 2 by suitable securing elements such asset screws 14.

The intensity of magnetic field or attraction and relative weight ofsaid permanent magnet 3 are predetermined so that the gravitational pullis counteracted by the attraction on the magnetic field at any height orlevel of the plate 2 generally when the resultant magnetic force isabove the center of gravity of said permanent magnet. But when theresultant force of magnetic attraction by the object such as the sheets16 approaches the center of gravity of the magnet 3, then the downwardcomponent force prevails and the permanent magnet 3 slides along saidsurface 6 until the horizontal magnetic attraction forces by the sheets16 have a resultant force above the center of gravity sufiicient toovercome the gravity force and thus hold the magnetic plate 3 inposition.

The aforesaid balancing of the magnetic forces occurs automaticallyduring the separation and removal of the magnetic sheets 16. A stack ofmagnetic sheets 16 is placed in the usual position for operation whereit is necessary to remove them from the stack, one by one. Then themagnetic separator as heretofore described is placed along the edge ofsaid stack of sheets 16 and the magnet 3 is pulled up to its topposition as shown in Fig. 3. This magnetic pull separates several of thesheets 16 at the top of the stack and pulls the ends of said sheets 16adjacent to said plate 1 upwardly as shown in Fig. 3.

Thus the force of magnetic attraction by the sheets 16 horizontally uponthe entire magnet 3 is divided over the entire surface of the magnet 3and its magnetic field in its upper as well as in its lower area,respectively above and below the center of gravity of the magnet 3. Themag net 3 is thus held in position by the sheets 16 and vice versa. Whenthe top separated sheet 16 is removed, then the horizontal magneticforce is lessened and the resultant horizontal component is lowered.After the removal of several top sheets 16, vertical gravity componentsare sufficient to overcome the horizontal component and to slide themagnet down on the surface 6 to a position where the next raised sheets16 exert suflicient horizontal magnetic attraction to hold the magnet 3.As the magnet 3 is lowered, its lower area raises the inner edges ofadditional sheets 16 from the stack. Thus in sequence the top magneticsheets 16 are removed from the stack and the magnet 3 gradually slidesdown in proportion to the sheets 2 removed to a position where themagnet holds the previously raised magnetic sheets 16 and is heldthereby in raised position and also separates additional sheets 16 fromthe stack until all the sheets 16 on the stack are separated and removedand the magnet 3 reaches the bottom of the housing 2.

While the exact equation of forces as between the attraction and thegravity and the frictional systems are not exactly known, neverthelessin actual operation of the model constructed in accordance with thisinvention, this self adjustment of the magnet during the separation andremoval of magnetic sheets from stack is accomplished by a singleslidable magnet.

Fig. 3 illustrates the position of the magnet 5 where the upper area ofthe magnetic field is occupied or attracted by a number of raised sheets16. Fig. 4 illustrates the position where a number of sheets 16 wereremoved and the relative magnetic attraction was lessened to a degreeincapable of resisting gravity forces on the magnet 3, hence the magnet3 slides down to the position shown in Fig. 5 where again a sufiicientnumber of sheets 16 are raised into the upper area magnetic field toresist gravity action on the magnet 3.

Iclaim:

l. A magnetic device for separating the top sheets from a stack ofsheets of magnetic material comprising a generally vertical non magneticguide element beside the stack, one side of-said element being adaptedto guide the edges of said sheets at the adjacent side of said stack, amagnet slidable along the other side of said element and being adaptedto hold adjacent edges of several top sheets raised from said stack, themagnetic field between said raised sheets and said magnet and the forceof gravity on said magnet interacting to lower said magnet and raisefurther sheets from said stack 4 substantially in proportion to theremoval of top sheets from the stack.

2. A magnetic device for separating the top sheets from a stack ofsheets of magnetic material, comprising a generally verticalnon-magnetic plate, a first face of said plate contacting the edges ofthe sheets on a side of said stack, a magnet freely slidable along theother face of said plate, the said magnet being so proportionedrelatively to said stack of sheets as to raise sheets at the top of thestack and be held stationary by the magnetic forces between said raisedsheets and the magnet and to be permitted to slide downwardly insubstantial proportion to the removal of said raised sheets from thestack.

The method of magnetic separation of sheets of magnetic material fromstacks, comprising the steps of 1 reely positioning a permanent magneton a non-magnetic plate opposite the top of said stack so as to raisesheets from said stack so that magnetic attraction by said raised sheetsovercomes the action of gravity, and removing raised sheets from thestack in sequence until said gravity overcomes said magnetic attractionand lowers the magnet on said plate relatively to said stack so as toraise more adjacent sheets from the stack.

References Cited in the file of this patent UNITED STATES PATENTS1,716,602 Ross June 11, 1929 2,341,639 Mathiesen Feb. 15, 1944 2,474,141Chatterton June 2, 1949 2,650,092 Wall Aug. 25, 1953 2,667,394 Goetz eta1. Jan. 26, 1954

